// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_MESSAGE_PORT_SERVICE_H_
#define CONTENT_BROWSER_MESSAGE_PORT_SERVICE_H_

#include <map>
#include <utility>
#include <vector>

#include "base/macros.h"
#include "base/memory/singleton.h"
#include "base/strings/string16.h"
#include "content/common/content_export.h"
#include "ipc/ipc_message.h"

namespace content {
class MessagePortDelegate;

class CONTENT_EXPORT MessagePortService {
public:
    typedef std::vector<std::pair<base::string16, std::vector<int>>>
        QueuedMessages;

    // Returns the MessagePortService singleton.
    static MessagePortService* GetInstance();

    // These methods correspond to the message port related IPCs.
    void Create(int route_id,
        MessagePortDelegate* delegate,
        int* message_port_id);
    void Destroy(int message_port_id);
    void Entangle(int local_message_port_id, int remote_message_port_id);
    void PostMessage(
        int sender_message_port_id,
        const base::string16& message,
        const std::vector<int>& sent_message_ports);
    void QueueMessages(int message_port_id);
    void SendQueuedMessages(int message_port_id,
        const QueuedMessages& queued_messages);
    void ReleaseMessages(int message_port_id);

    // Updates the information needed to reach a message port when it's sent to a
    // (possibly different) process.
    void UpdateMessagePort(int message_port_id,
        MessagePortDelegate* delegate,
        int routing_id);

    // Returns the current information by which a message port can be reached.
    // Either |delegate| or |routing_id| can be null, in which case that bit of
    // information is not returned.
    void GetMessagePortInfo(int message_port_id,
        MessagePortDelegate** delegate,
        int* routing_id);

    // The message port is being transferred to a new renderer process, but the
    // code doing that isn't able to immediately update the message port with a
    // new filter and routing_id. This queues up all messages sent to this port
    // until later ReleaseMessages is called for this port (this will happen
    // automatically as soon as a WebMessagePortChannelImpl instance is created
    // for this port in the renderer. The browser side code is still responsible
    // for updating the port with a new filter before that happens. If ultimately
    // transfering the port to a new process fails, ClosePort should be called to
    // clean up the port.
    void HoldMessages(int message_port_id);

    // Returns true if messages for a message port are on hold.
    bool AreMessagesHeld(int message_port_id);

    // Closes and cleans up the message port.
    void ClosePort(int message_port_id);

    void OnMessagePortDelegateClosing(MessagePortDelegate* filter);

    // Attempts to send the queued messages for a message port.
    void SendQueuedMessagesIfPossible(int message_port_id);

private:
    friend struct base::DefaultSingletonTraits<MessagePortService>;

    MessagePortService();
    ~MessagePortService();

    void PostMessageTo(
        int message_port_id,
        const base::string16& message,
        const std::vector<int>& sent_message_ports);

    // Handles the details of removing a message port id. Before calling this,
    // verify that the message port id exists.
    void Erase(int message_port_id);

    struct MessagePort;
    typedef std::map<int, MessagePort> MessagePorts;
    MessagePorts message_ports_;

    // We need globally unique identifiers for each message port.
    int next_message_port_id_;

    DISALLOW_COPY_AND_ASSIGN(MessagePortService);
};

} // namespace content

#endif // CONTENT_BROWSER_MESSAGE_PORT_SERVICE_H_
